From waste to biomethane, a circular revolution

From rubbish bins to the tanks of cars and buses: this is the second life of food waste, which from household kitchens returns to life after a long and complex production process to power private vehicles and public transport or for domestic use, ensuring benefits for the quality of the air and of the environment. Biofuel is indeed a new milestone for the Hera Group which, through its biomethane plant inaugurated in Emilia-Romagna, in S. Agata Bolognese (Bologna), continues on its path towards a circular economy, consolidating its leading position. Construction work on the plant began in April 2017 and in October 2018 biomethane started to flow into the network.

Hera has been producing biogas for some time to generate renewable electricity using biodigesters and landfills. But thanks to the new plant this biogas is refined to become, precisely, biomethane, a 100% renewable fuel.

Artistic photography Silvia Camporesi

Organic waste undergoes an anaerobic biodigestion process in the new plant built by Hera, the first multi-utility in Italy to construct one. In essence, the plant shreds screened waste and processes it for about 21 days in four horizontal, hermetically sealed digesters, in which micro-organisms anaerobically biodigest it to produce the biogas that, at a later stage, is refined (up-graded) by running through a counter-current of pressurised water. At this stage, the carbon dioxide is separated from the methane to obtain biomethane, a gas that is over 95% methane and that is an entirely renewable source.

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At the end of the anaerobic biodigestion process, other material is added to the resulting solid organic matter to obtain a compact mass that is sent to composting, to produce quality compost, which can be used as a fertiliser in agriculture or as potting soil.

At full capacity, on a yearly basis, 100,000 tonnes of organic waste from separate waste collection plus 35,000 tonnes of green waste and pruning material can be used to obtain 20,000 tonnes of compost and 7.5 million cubic metres of biomethane, avoiding the use of fossil fuel equal to over 6,000 tonnes of oil equivalent (toe) per year, and thus the release of 14,000 tonnes of CO2.

It is, therefore, an initiative that if replicated, can significantly contribute to Italy's energy strategy and to achieve the European 20-20-20 targets.

Hera is the Italian multi-utility that improves every day, with regard to the environment, the quality of its waste management, water and energy services through strong links in the area in which it operates and the capacity for innovation